It is a common production practice to release various dissolvable materials into oil and gas wells. These materials are often stick shaped.
For example, an oil and gas well's production of hydrocarbons is often terminated by the presence of produced formation water in the well. This occurs when a column of such water has a hydrostatic pressure higher than the pressure of the producing formation. To prevent this from occurring, it is common to periodically release "soap" sticks into the well which, when dissolved, will decrease the hydrostatic pressure of the fluid column to an extent which allows the formation to continue to flow.
The actual release of such sticks is typically done by hand, although mechanical stick release devices are now in use. One such stick release mechanism is found in U.S. Pat. No. 5,188,178, which teaches a device and related methods, involving an enclosed magazine holding several sticks. It has the ability to rotate each stick into a position to be dropped into the well. A disadvantage present in this device is that the entire top of the magazine enclosure must be removed for loading the sticks into the magazine. Furthermore, the top of the device is flat which is not an optimum design for handling high pressure in an enclosure.
An electric motor is suggested for rotating the magazine in this device, which fails to take advantage of the available well gas pressure for this purpose.
Other disadvantages of this device is a lack of total isolation from well pressure during the typical reloading process, and the absence of an emergency shut down feature for events of unusually high well pressure. The device is isolated from well liquids only, using a check valve which is not pressure sensitive. The check valve also introduces a reduction of internal diameter in the path followed by the stick.
Another known device, that of J & J Oilfield & Electric Service, utilizes well gas pressure to automatically open a number of valves positioned in series between each pipe nipple section in a vertically oriented single line. The valves are opened from the bottom up, and pipe nipple holds two sticks of material, with the higher section dropping sticks through the previously emptied lower section. A disadvantage is that the number of releases is limited to approximately two, because of the undesirable height associated with additional sections. Similarly, the person reloading the device must climb a significant height to load the device.
What is needed is an automatic stick launcher for releasing such sticks, which has a simple method of loading, total isolation of the magazine from well pressure and liquids during reloading, optimum housing structural integrity, adequate provisions for higher pressure wells, an ability to operate almost entirely from available well pressure, and an emergency shut down system in the event the well over pressures.